Tetracycline is an antibiotic medication used to treat a variety of bacterial infections. It belongs to a group of medicines known as tetracycline antibiotics and works by interfering with the ability of bacteria to produce essential proteins. This prevents the bacteria from growing and multiplying. Tetracycline may be used for certain infections affecting the skin, respiratory system, and other parts of the body. Because antibiotics are intended for bacterial infections, they do not work against viral illnesses such as the common cold or flu.